Apparatus for burning liquid fuel



Jan. 5, 1937. R SHERMAN 2,066,651

APPARATUS FOR BURNING LIQUID FUEL Filed March 29, 1934 3 Sheets-Sheet l liafgl 82 Jan. 5, 1937. R. M. SHERMAN APPARATUS FOR BURNING LIQUID FUEL Filed March 29, 1934 5 Sheets-Sheet 2 Jan. 5, 1937. R. M. SHERMAN APPARATUS FOR BURNING LIQUID FUEL Filed March 29, 1934 3 Sheets-Sheet 3 46 S33 mm ENSEQ .6

Patented Jan. 5, 1937 2,066,651

UNITED STATES PATENTOFFlCE APPARATUS FOR BURNING LIQUID FUEL Rallston M. Sherman, Glastonbury, Coma, assignor to The Silent Glow Oil Burner Corporation, Hartford, Conn, a corporation of Connecticut Application March 29, 1934, Serial No. 717,967

Claims. (Cl. 158-76) This invention relates to apparatus for burning liquid fuel (herein referred to for description as oil) and deals more particularly with burners of the so-called gun type. The invention has, among thin, torch-like name with smoky ends. it the air dispersion is such that there is a discharge of a substantial amount of free oil outside of the air stream, there results an irregular and generally 5 other objects, the improvement of conditions of smoky flame. In either case, the flame has no 5 combustion pertaining to. this type of burner, to stable or well-defined pos but is bje t to increase the efllciency of such burners by reducing a wavering or flickering action, this being parthe power required for effectively burning fuel ticularly noticeable in the fluctuating position of supplied at any given rate, and to simplify the the point where the flame is initiated ahead of construction by reducing expense of manufacture the nozzle. 10 and rendering the burner conveniently accessible Where devices for imparting the rotary moveafter installation for purposes of cleaning, repair ment to the air have assumed the common form or readjustment. of fixed, broad, helical blades of relatively sharp In burners of the common form of so-called pitch, mounted on and radiating from the cengun type, liquid fuel is delivered under relatrally positioned nozzle pipe, they have not only 15 ely high pressure to a nozzle, from which it is impeded the passage of air, increasing the power discharged without premixture with air through required for operating the burner, but have crea relatively small nozzle into the combustion ated an air turbulence destroying in part the true chamber of a furnace in the form of an expanding rotary movement of the air mass and leadin to cone-shaped spray of finely atomized oil. To a dispersion of the air in the combustion chamber. 2 provide a combustible mixture, air is discharged which tends to aggravate the absence of coinc1- into the combustion chamber usually under the dence referred to. forced draft of a'fan or blower, and through a The present invention has, among other objects, conduit surrounding the nozzle and opening into imparting to the air mass traveling through the t the combustion chamber, the latter being othert ular conduit a helical or rotary movement un-. 25 wise sealed off so that substantially the entire der hi momentum and the i air supply available for combu tion i deli red helically moving mass of air on emergence into through such conduit about the nozzle and is inthe combustion chamber with relation to an extended to intermingle with the atomized oil. panding cone-like oil spray, such that there is 80 In an attempt to enforce e intermingling of established the required coincidence between the the atomized 011 Spray d e ir d scharged air and the oil spray when released in the combusfrom the mouth of the conduit, devices have tion chamber, and the desired fat, bushy, steady been employed designed to impart a helical or flame is p oduced.

rotary movement to the air passing through This and other objects of the invention will be the conduit for the impose ofsecuring more best understood by reference to the following deil'ltlm'ete intermlngling O the a r and the oil scription when taken in connection with the acspray. Such devices, however, have failed to companylng illustration, while its scope will be produce the desired type of flame, which should re particularly pointed out in the appended be a fat, bushy, bright, smokeless flame, evldenc l lm 4o 40 ing complete combustion, and having a firm, sta- In the drawings:

ble, well defined and unwavering position. This Fig. 1 is a front view of a burner embodying I have discovered is due to the failure to so conone form of the invention and looking back from trol the progressively and. helically moving body the mouth of the burner nozzle;

of air on its emergence or release into the com- Fig, 2 is a cross-sectional elevation of the con- 45 bustion chamber from the mouth of the conduit,

and to so relate it to the expanding oil spray, that there shall be the required coincidence of movement and position between the released air and oil spray. If the dispersion of air to the combustion chamber is so out of colncldence'with the v dispersion of the oil spray that a substantial amount of the free air required for combustion is discharged into the combustion chamber outside of the air spray, there results an undesirable duit on the line 2-2 of Fig. 3, looking in the direction of the arrow;

Fig. 3 is a detail in cross-sectional elevation showing the forward portion of the tubular conduit;

the upper one of the two separable parts of the casing, showing such part removed;

Fig. 5 is a side elevation of the lower one of the two separable parts of the casing, showing- 50 Fig. 4 is a sectional elevation taken through emergence into the combustion chamber.

Referring to the embodiment of the invention here submitted for illustrative purposes, the burner is equipped (Figs. 5 and '7) with a rotary air impeller having a central air intake and of the so-called Sirocco type. The impeller is mounted on a driving shaft l3 and comprises a disk l5 and a spaced opposed annular plate H, with interconnecting multiple vanes or blades. On one side of the impeller and connected to the driving shaft I3 is mounted the electric driving motor l9 (Fig. 1), and on its opposite side and connected to the prolonged end of the driving shaft is the oil pump 2|.

The impeller is contained within a housing 22, the upper part of which is of a generally cylindrical form, having its end wall or head facing the motor closed except for the opening through which the driving shaft extends, and the opposite side or end wall facing the pump providing an air admission opening 23 aligned with the opening of the annular plate H of the impeller. The amount of air admitted through the air admission opening is controlled by a disk-shaped shutter 25 (Fig. 1) which may be adjusted to a fixed position after the burner has been installed and its air requirements determined.

The impeller, which rotates in the'direction of the arrow shown in Fig. 5, is mounted in eccentric relation to the peripheral walls of the housing 22, so that the clearance between such walls and the impeller is at a minimum at the point designated 21 in Figs. 4 and 6 (which may be termed the point of air registry), but gradually increases from that point to the air discharge portion of the housing at the bottom thereof. At the bottom or air discharge portion of the housing, the' latter merges into a prolonged, straight, cylindrical, tubular air conduit member 29 having an open mouth at its forward end and extending in a general direction at right angles to the axis of rotation of the impeller and in a tangential relation to the discharge portion of the housing, so that the mass of air is urged in a straight line direction from the impeller to the mouth of the conduit without other obstruction than is offered by the parts contained in the conduit and hereinafter described.

Positioned axially within the conduit is an oil delivery pipe 3|, terminating just short of the conduit mouth in a nozzle 33, and entering the conduit at one side at 35, where it has external connection to the oil supply pipe 31 extending to the discharge side of the pump 2|, the supply pipe 38 for the pump being connected to any suitable source of supply (not shown), such as a main storage tank. The usual accessories, such as reducing valves, strainers, etc., are omitted for the sake of simplicity. Liquid oil without premixture with air is supplied by the pump to the nozzle at a relatively high pressure, as between and 135 pounds and preferably within the neighborhood of pounds per square inch, so that a high pressure mechanical atomization is produced at the nozzle, the liquid oil being discharged therefrom in the form of a coneshaped spray subtending an angle which may vary according to the type of nozzle employed, but which is usually between 45 and 80 degrees.

To ignite the commingled oil and air, one or more sparking electrodes 4| (herein two in number) are employed positioned in advance of the nozzle and connected each to a conductor 43, the latter being mounted in rigid, non-conducting sleeves 45 of porcelain or other like insulating material, the conductors entering the conduit through the bottom walls thereof at the points designated 41 in Figs. 6 and '7.

The motor rests on and is secured to a plate or shelf 49, and the pump rests on and is secured to a similar plate 5|, both of which may be formed integrally with the impeller housing. Lugs 53, 55, 51 and 59, depending respectively from the motor plate 49, pump plate 5|, impeller housing 22 and the conduit 29, provide means for attaching the burner to supporting legs or other supporting means when the burner is installed. On the installation of the burner, the forward end of the conduit is entered into and sealed within the walls 6| (Fig. 7) of the combustion chamber of the furnace, the open mouth of the conduit terminating preferably substantially flush with the inner walls of the combustion chamber, and the combustion chamber being sealed against any substantial admission of air other than that delivered through the conduit, so that substantially the entire air supply for combustion is delivered through and released from the open mouth of the conduit about the liquid oil spray delivered from the nozzle 33.

To maintain the nozzle in central position and the electrodes in fixed relation to the nozzle, a support 63 is provided in the forward end of the conduit (Figs. 2 and 3), and to reduce to a minimum the obstruction to air flow, such support is formed by bending up three pieces of thin sheet-metal which are screwed or clamped together about the sleeves 45 and the oil pipe 3|, thereby providing a three-point sheet-metal support presented edgewise to the air flow and fitting loosely against the inner walls of the conduit.

After the burner has been installed occasional inspection of the nozzle and electrode connections may be required. Continued use also tends to the accumulation of dirt and dust on the blades of the impeller, reducing its efllciency and affecting the combustion by reducing the amount of air which should be supplied. As a means for providing instant access both to the impeller and to the nozzle and electrode connections, and at the same time as a means for materially simplifying the construction and reducing the cost of manufacture, I have formed the entire casing for the enclosed burner parts out of two interfitting but separable castings. Such casing comprises both the impeller housing and the tubular conduit, and with these also, in the illustrated embodiment of the invention, it additionally comprises the supporting parts for the motor and pump extending laterally from the impeller housing. i

As shown in the drawings, the casing comprises a lower casting (Figs. 5 and 7) which includes substantially the lower half 22 01' the impeller housing 22 (with the attached plates 49 and 5|), the entire forward part 29 of the tubular conduit unbroken and intact where it passes through the combustion chamber walls, and substantially the lower half of the intermediate portion 29 of said conduit. Such casing further compr es in.-

terfitting and separable upper casting (Fig. 4) which is removable as a single piece, and includes substantially the upper or companion half 22' of the impeller housing, carrying the point 21 of air registry and the upper or companion half 29 of said intermediate portion of the conduit. The upper separable part of the casing is provided (Fig. 4) with a curved or flanged front wall 65, the bottom wall 61 and the back wall 69 adapted to lie and fit over the opposed mating walls of the lower part. A small depending lug H on the back wall 69 and a similar lug 13 on the bottom wall M at each opposite side of the portion 29 provide each a threaded seat for a single set screw, so that, when applied in place, the upper portion may be fastened securely but may be instantly removed after loosening the three set screws.

It will be observed that the separation of the two parts is along a horizontal plane in the impeller housing, intersecting the axis of the impeller, and a horizontal plane coinciding substantially with the axis of the conduit and along an intermediate plane extending diagonally from the axis of the impeller to the point of the lateral entrance of the oil nozzle pipe, the connection of the later, however, being left intact in the lower one of the two separable parts.

The result is that the entire casing and support for the burner parts are produced from two relatively simple castings, avoiding the necessity of the careful and expensive machine work usually required, and, after the burner is installed, all working parts of the burner within the casing (as indicated in Figs. 5 and 7) may be instantly opened up for inspection, cleaning, repair or adjustment by merely loosening and lifting away the single separable upper part of the casing.

Features relating to the described construction of the housingand the tubular air conduit are the subjectof my divisional application, Serial No. 43,238, filed Oct. 2, 1935.

Referring now to the features bearing more directly on the improvement in conditions of combustion, I have found that it is not only necessary to bring the air into coincident relation with the oil spray, but that for such coincidence and to properly control the air dispersion on release into the combustion chamber it is necessary that the air leave the mouth of the conduit with the air particles traveling helically under high momentum, with an absence of any substantial irregular turbulence.

For this purpose means are employed for progressively impressing on the body of air forced through the conduit a rotary motion, such means comprising (Figs. 3 and 8) a series of helically disposed ribs or vanes l5 (herein eight in number) extending inwardly from the inner walls of the forward part 29 of the tubular conduit and extending back from the mouth of the conduit through the cylindrical and uncontracted portion thereof for nearly half the length of the conduit.

These ribs are of relatively low or flat pitch,

but, if desired, the pitch may progressively increase or become sharper from the impeller end of the conduit toward the mouth thereof. The ribs are of relatively small height, but may progressively increase in height toward the conduit mouth, or preferably (as shown in Figs. 2 and 8) may remain of the same height for the major portion of their length and be sharply and materially increased in height (as indicated at 15*) near the mouth of the conduit, such increase beginning, however, a substantial distance back of the nozzle.

As shown in Fig. 8, which, in the Bristol board drawing accompanying the application, is a full size cross-section of the forward end of a conduit embodied in an illustrative example of the invention, the mouth of the conduit is sharply contracted and the cylindrical interior terminates thereat in an inwardly tapered wall 'l'l inclined at a well defined angle. The ribs extend to the edge of the conduit mouth and so increase in height that their inner edges coincide with the periphery of the conduit mouth, the conduit abruptly terminating thereat, so that the air has impressed upon it the full rotating eifect of the ribs up to the time of its release, such rotating effect reaching a maximum before it encounters any contraction in the conduit. The air therefore emerges into the combustion chamber as a progressively moving mass rotating under a high momentum and without substantial interfering turbulence.

As a numerical example, the specific construction illustrated in Figs. 3 and 8 may be instanced. There, the ribs have a length of approximately 8 inches, the conduit having an inside diameter of 3 inches. and the pitch of the ribs at the conduit mouth is at the rate of one turn in 32 inches. That pitch of the ribs, if desired, may be gradually decreased or flattened toward their opposite ends until a pitch at the rate ,of one turn in 45 or 60 inches is reached, or the pitch may remain unchanged throughout their length. In such specific example, the ribs may be about /8 of an inch in height for the major portion of their length, reaching a height at it adjacent the conduit mouth of approximately of an inch, the mouth of the conduit being contracted to an inside diameter of 2% inches and the angle of the tapered wall ll over and in contact with which the air is discharged being approximately 45 degrees.

Since a straight cylindrical conduit is provided extending back from its mouth in tangential relation to the discharge portion of the impeller housing, a substantially straight-way and unimpeded passage is presented to the air from the point where it is delivered by the impeller to'the point where it is released from the conduit. As soon as the ribs are encountered the advancing movement of the air under the action of the impeller is converted in part into a rotary mass movement. The helical ribs, extending as they do well back into the uncontracted part of the cylindrical conduit. effect at the beginning a slow movement of rotation which progressively increases in intensity until the air reaches the mouth of the conduit where such rotating effect is at a. maximum. the result being that with a minimum expenditure of power at the impeller a high momentum, rotary movement of the entire mass of air is obtained at the point of air emergence without the production of interfering air turbulences.

This provides for a controlled and well defined emergence of the air into the combustion chamber, which may be idealistically represented in Figi- 8. The entire air mass rotating under high momentum, on reaching the end of the conduit, encounters the tapered wall ill by means of which it is caused to contract so that it becomes in effect, and emerges from the contracted mouth as, a contracting helix of progressively moving air. This effect persists for some distance in front of the mouth of the conduit, the air helix continuing to contract until a point (such as indicated at 19 in Fig. 8) is reached where further contraction ceases and it tends to become an expanding helix of advancing air.

To properly coordinate with the oil spray this rotating and progressively moving air mass, which first contracts and then tends to expand, the oil nozzle 33 is so positioned that the periphery of the cone-shaped spray will be brought into substantially coincident and tangential relation to the periphery of the helical air mass at or about the point 19 where the latter begins to expand.

The result is that from this point on each particle of air (comprising substantially all the air supplied for combustion) has a movement which is compounded of a rotary movement cutting transversely across the path of the oil particles comprising the spray and a linear progressive movement which closely coincides in direction with the linear progressive movement of the particles comprising the oil spray.

After a point is reached approximating the point of coincidence 19, there follows substantially no tendency for the dispersion of oil particles outside of, the enveloping and expanding air helix, so that a smoky flame due to this cause is eliminated, and there is substantially no tendency for the dispersion of any substantial amount of air required for combustion outside of the expanding cone of oil spray so that the tendency to form a thin torch-like flame along the axis of the cone is also prevented. The result is the production of a cone-shaped oil spray up to the point 19, substantially as shown in Fig. '7 (which can readily be observed in the combustion chamber), beyond which, and beginning with a fixed, stable point or zone coinciding substantially with the point of coincidence, there occurs a bright, fat, bushy and well defined smokeless flame having an unwavering and well defined position.

It is important that the nozzle mouth be positioned so as to secure the described coincidence of air mass and oil spray, and such position will depend in part upon the angle subtended by the spray and in part upon the velocity of the air. In the specific example offered for illustration, the nozzle has a mouth corresponding to the diameter of a No; 76 drill, or approximately .020 inch, designed to be used with an oil supply under approximately pounds of pressure, and with an air supply delivered through the described conduit and conduit mouth adjusted to burn approximately three gallons of oil per hour. With a nozzle having a mouth of the dimensions indicated and working under the conditions described, a cone-shaped spray will be produced having an angle of dispersion approximately 45 degrees. This nozzle is positioned approximately of an inch back of the conduit mouth, thus bringing the oil spray and rotary air mass into such a relation of approximate coincidence that the results described are secured.

If a nozzle is employed forming a wider angle of oil spray, the nozzle should be advanced, and if it forms a sharper angle it should be retracted. In the illustrative example given, if a nozzle or pressure is employed so that the angle subtended by the oil spray approximates 60 degrees, the nozzle should be advanced by about A; of an inch so as to be positioned about of an inch back from the conduit mouth.

The position of the oil nozzle indicated in the foregoing numerical examples is with reference to an air velocity represented by a static pressure in the air conduit of approximately .04 inch of water.

With the described form and dimensions of conduit and conduit mouth, if the air velocity is diminished so that the air helix continues to contract only for a lesser distance from the mouth of the conduit the nozzle should be retracted, and if such air velocity is increased it should be advanced. Since the air supply and velocity may be subject to some slight adjustment when the burner is first installed, provision is made for the adjustment of the nozzle 33 on the nozzle pipe 3|, or an adjustment provided in the nozzle pipe itself, to afford the relatively small range of nozzle adjustment indicated by the foregoing.

While I have herein shown for the purposes of illustration one specific embodiment of the invention, it is to be understood that the dimensional examples given, as well as the details of construction shown or referred to, are for illustration I only, and that wide variations may be made in the details and features of construction and the relative arrangement of parts, all without departing from the spirit of the invention.

I claim:

1. For association with and as substantially the sole fuel and air source for a combustion chamber, a liquid fuel burner comprising a cylindrical air conduit having a contracted mouth and extending rearwardly therefrom for a substantial distance to provide a straight-way passage for air therethrough, an impeller arranged to force air through said conduit, a spray nozzle axially located in said conduit near but rearward of the contracted mouth thereof and means for supplying liquid fuel under pressure to said nozzle, said nozzle being adapted to provide a high-pressure mechanically atomized cone-shaped spray discharged through the mouth of said conduit, and means comprising angularly disposed elements on the inner wall of said conduit extending rearwardly for a substantial distance behind said nozzle and arranged to impart a high-momentum rotary movement to air moving through said conduit before it passes through the contracted mouth so as to cause vortical motion of air discharged through said mouth.

2. A liquid fuel burner comprising an air impeller, a tubular air conduit having a contracted mouth and arranged to receive air from said impeller under pressure and discharge the same through the mouth, a spray nozzle having an orifice formed to produce a cone-shaped spray of fuel and axially positioned in said conduit near the mouth thereof to discharge said spray cone from said mouth, means for supplying liquid fuel under pressure to said nozzle, prolonged helically disposed vanes of relatively flat pitch projecting inwardly part way across the conduit from the inner wall of the conduit and extending lengthwise of the same from a position ahead of said nozzle for a substantial distance rearward of said nozzle and adapted to impart to air passing through said conduit a high momentum, helical, non-turbulent movement gradually accelerated to the conduit mouth, thereby to cause the body of advancing air to contract on emergence and then expand into substantial coincidence with said spray cone.

3. A liquid fuel burner according to claim 2 in which said vanes have a pitch of less than 45 and extend rearwardly from a point adjacent the mouth of the conduit for a distance not less than the internal diameter of the conduit.

4. For association with and as substantially the sole fuel and airsource for a combustion chamher, a liquid fuel burner comprising a substantially straight cylindrical air conduit having a contracted mouth presenting a tapered wall inclined at a substantial angle, an impeller arranged to force air through said conduit, a spray nozzle axially located in said conduit near but rearward of the contracted mouth thereof and means for supplying liquid fuel under pressure and unmixed with air to said nozzle, adapted to produce a high-pressure mechanically atomized coneshaped spray discharging through the mouth of said conduit, and helically disposed ribs on the inner wall of said conduit extending rearwardly from the mouth for a substantial distance behind the said nozzle and having an increasing pitch toward the mouth, said ribs being adapted to produce a vortical motion of air discharged through the conduit mouth.

5. For association with and as substantially the sole fuel and air source for a combustion chamber, a liquid fuel burner comprising a cylindrical air conduit having a contracted mouth and extending rearwardly therefrom for a substantial distance to provide a straight-way passage for air therethrough, an impeller arranged to force air through said conduit, a spray nozzle axially located in said conduit near but rearward of the contracted mouth thereof and means for supplying liquid fuel under pressure and unmixed with air to said nozzle, adapted to produce a highpressure mechanically atomized cone-shaped spray discharged through the mouth of said conduit, and helically disposed ribs on the inner wall of said conduit extending rearwardly from the mouth for a substantial distance behind said noz- 21c and having an increasing height at their forward ends for imparting a high-momentum rotary movement to air moving through said conduit before it passes through the contracted mouth, thereby producing a vortical motion of air discharged through said mouth.

RALLSTON M. SHERMAN. 

